This invention relates generally to robotic systems, and more particularly to controllers for robot manipulators.
Various robotic system have been disclosed in the patent literature and are commercially available. Such systems frequently include a manipulator arm for supporting a tool at its free end to move the tool to desired spatial positions to accomplish some desired task, e.g., handling parts for assembly operations, machine loading applications, etc.
The manipulator arms used in such systems are frequently jointed so that the tool can be moved to any position within a three-dimensional envelope, commonly referred to as the working envelope of the arm. One common practice is to form the arm of plural joints with interconnecting links so that the arm is arranged to be moved to simulate movements of a human arm. Hence, such arms frequently include a shoulder joint for rotating the arm about a horizontal axis, a wrist joint for rotating the tool holder about a pitch or a roll axis, etc. The actual movement of the joints of the arm is accomplished by motors or other actuators. The operation of the motors is usually accomplished under computer control. In this regard, in state-of-the-art robotic systems, the arms are controlled by computer means which include microprocessors for effecting movement of the arm to various positions within the working volume in accordance with predetermined teachable and repeatable programs. To accomplish such computer control, the joint motors frequently have associated with them encoders to provide signals indicative of joint position. These signals are operated on by mathematical computating means in the system's microprocessors so that the exact position of the tool within the working volume is determined to insure accurate arm positioning when the joint motors are operated to move the arm to another position within the working volume.
While such prior art systems are generally suitable for their intended purposes, the interconnections between the microprocessors of the system's controller provides severe constraints on future growth of the system. In this regard, in some prior art systems in order to add additional processing capabilities, diagnostics, and memory, substantial modification to the circuitry forming the controller is necessary.